Final answer:
Proteins are necessary for synthesizing enzymes, hormones, neurotransmitters, antibodies, and transport proteins because they supply essential amino acids, some of which must be sourced from the diet.
Step-by-step explanation:
An adequate supply of proteins is needed for the synthesis of enzymes, hormones, neurotransmitters, antibodies, and transport protein.
While carbohydrates provide energy in the form of ATP, via metabolic pathways, it is proteins that supply the amino acids essential for building cellular components like enzymes and hormones.
Moreover, certain amino acids cannot be synthesized by the body and must be obtained through the diet. Fats and vitamins are also necessary for health; fats contribute to energy and the absorption of fat-soluble vitamins, while vitamins are essential in small quantities for various functions, including enzymatic activity.